* How to handle kprobe bugs?
@ 2011-03-30 13:53 Tixy
2011-03-30 14:10 ` Dave Martin
0 siblings, 1 reply; 4+ messages in thread
From: Tixy @ 2011-03-30 13:53 UTC (permalink / raw)
To: linux-arm-kernel
Now that I'm writing some test code for kprobes I'm quickly finding
further bugs with the instruction emulation. E.g. ALU ops with an
immediate operand are broke. Shall I wait until I have completed writing
all test cases before submitting a single fix patch? (It could be a
couple of weeks.)
I also find that instruction emulation for some (all?) ARMv6K and newer
instructions are missing. E.g. hint instructions like NOP and WFI. Shall
I produce a second patch to add these?
At some point I will also get around to doing my original task of adding
Thumb support to kprobes. I'm assuming that fixing ARM code is higher
priority than adding Thumb support?
--
Tixy
^ permalink raw reply [flat|nested] 4+ messages in thread
* How to handle kprobe bugs?
2011-03-30 13:53 How to handle kprobe bugs? Tixy
@ 2011-03-30 14:10 ` Dave Martin
2011-03-30 18:34 ` Tixy
0 siblings, 1 reply; 4+ messages in thread
From: Dave Martin @ 2011-03-30 14:10 UTC (permalink / raw)
To: linux-arm-kernel
On Wed, Mar 30, 2011 at 02:53:33PM +0100, Tixy wrote:
> Now that I'm writing some test code for kprobes I'm quickly finding
> further bugs with the instruction emulation. E.g. ALU ops with an
> immediate operand are broke. Shall I wait until I have completed writing
Good spot ... if so, this definitely needs fixing(!)
> all test cases before submitting a single fix patch? (It could be a
> couple of weeks.)
My view (others may differ):
If there are several independent fixes, that's probably best presented
as multiple patches; but it may be better to post them as a series when
you're done.
I expect this will be more digestible for people than a trickle of
patches over a longer period, unless the total changeset becomes
large.
>
> I also find that instruction emulation for some (all?) ARMv6K and newer
> instructions are missing. E.g. hint instructions like NOP and WFI. Shall
> I produce a second patch to add these?
Sure.
Note that you should emulate all the hinted NOPs as actual NOPs,
since the event the hint waits for may happen in the meantime;
under some circumstances that would lead to stalls.
>
> At some point I will also get around to doing my original task of adding
> Thumb support to kprobes. I'm assuming that fixing ARM code is higher
> priority than adding Thumb support?
I think that's reasonable, provided there is not too much work to do
to fix the ARM case -- it sounds like there isn't much to fix, but
please shout otherwise.
Cheers
---Dave
^ permalink raw reply [flat|nested] 4+ messages in thread
* How to handle kprobe bugs?
2011-03-30 14:10 ` Dave Martin
@ 2011-03-30 18:34 ` Tixy
2011-03-31 8:54 ` Dave Martin
0 siblings, 1 reply; 4+ messages in thread
From: Tixy @ 2011-03-30 18:34 UTC (permalink / raw)
To: linux-arm-kernel
On Wed, 2011-03-30 at 15:10 +0100, Dave Martin wrote:
> On Wed, Mar 30, 2011 at 02:53:33PM +0100, Tixy wrote:
> > I also find that instruction emulation for some (all?) ARMv6K and newer
> > instructions are missing. E.g. hint instructions like NOP and WFI. Shall
> > I produce a second patch to add these?
>
> Sure.
>
> Note that you should emulate all the hinted NOPs as actual NOPs,
> since the event the hint waits for may happen in the meantime;
> under some circumstances that would lead to stalls.
Good point :-) Conversely, things like Send Event shouldn't be actual
NOPs.
--
Tixy
^ permalink raw reply [flat|nested] 4+ messages in thread
* How to handle kprobe bugs?
2011-03-30 18:34 ` Tixy
@ 2011-03-31 8:54 ` Dave Martin
0 siblings, 0 replies; 4+ messages in thread
From: Dave Martin @ 2011-03-31 8:54 UTC (permalink / raw)
To: linux-arm-kernel
On Wed, Mar 30, 2011 at 7:34 PM, Tixy <tixy@yxit.co.uk> wrote:
> On Wed, 2011-03-30 at 15:10 +0100, Dave Martin wrote:
>> On Wed, Mar 30, 2011 at 02:53:33PM +0100, Tixy wrote:
>> > I also find that instruction emulation for some (all?) ARMv6K and newer
>> > instructions are missing. E.g. hint instructions like NOP and WFI. Shall
>> > I produce a second patch to add these?
>>
>> Sure.
>>
>> Note that you should emulate all the hinted NOPs as actual NOPs,
>> since the event the hint waits for may happen in the meantime;
>> under some circumstances that would lead to stalls.
>
> Good point :-) Conversely, things like Send Event shouldn't be actual
> NOPs.
Also a good point! For this one, I guess you'll need to take into
account what platform you're acutally running on, also.
Cheers
---Dave
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2011-03-31 8:54 UTC | newest]
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2011-03-30 13:53 How to handle kprobe bugs? Tixy
2011-03-30 14:10 ` Dave Martin
2011-03-30 18:34 ` Tixy
2011-03-31 8:54 ` Dave Martin
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